Electric discharge device



June 3, 1930. c. BOL ET AL ELECTRIC DISCHARGE DEVICE Filed March 15,1928 S N A M .u L" S S Y RB PM E O m N TS R N O EEE Wm" 1 M C Y BPatented June 3,- 1930 UNITE-D STATES PATENT OFFICE UORNELIS BOL, orEINDHOVEN, AND JOHANNES .mcauns HUMANS, or mnvnnsum,

NETHERLANDS, ASSIGNORS TO RADIO CORPORATION Tron or DELAWARE OI AMERICA,A CORPORA- ELEGTRIC DISCHARGE DEVICE Application filed March 15, 1928,Serial No. 261,833, and in the Netherlands March 10, 1927.

however, been found that in the case ofheavy high frequency currentsbeing introduced by a current lead which is secured to such a member,the latter may be strongly heated as a result of the hysteresis'lossesoccurring in it and which are caused by the magnetic field around thecurrent lead.

' The strong heating may result in the damage of the seal between themetal and the glass so that it is no longer hermetic, hence resulting intube deterioration. V

This invention has for its object the removal of the said disadvantageand to provide for an improved construction of the metal members used inconnection with the tube leads.

According to the invention a discharge tube, in which at least onecurrent lead to one of the electrodes within the tube is hermetica-llysealed by means of. a metallic member having its border sealedto theglass of the discharge tube,- is characterized in that on and adjacentthe seal the said member consists of iron "or an iron alloy and theremainder of. the material between the member and lead having smallhysteresis losses. Y v I .In order that any heat which possibly maystill be produced in the iron or the iron alloy, may be carried away, itmay be desirable that the material having small hysteresis losses shouldalso have a high thermal conductivity. In addition it is advisable to soshape the metallic member or to secure to this member so shaped parts ofto the magnetic field of electric currents in the current lead. I

As material having small hysteresis losses and a high thermalconductivity preferably copper may be employed. In addition it isdesirable that during the operation of the tube the seal should becooled by suitable cooling means, for example, by a liquid which flowsalong it or is squirted on to it.

The invention will be more clearly understood by reference to theembodiments shown in the accompanying drawing. In

the said drawing:

" Fig. 1 is a sectional view'of a current seal for an electrode, such asa grid, of a transmission valve; and

Fig. 2 shows a slightly different construction of such a'seal which alsois provided with a cooling device.

Referring to Fig. l, 1 is the glass tube wall which is sealed at 2 to aferrochrome bushing This bushing surrounds a copper disc 4 which hassecured to it a current lead 5 which is also of copper. This conductor 5serves to supply high frequency currents to one of the electrodes, asfor example, the grid of the transmission valve. The cylindrical copperscreens 6 and 7 are secured to the disc l so as to screen off theferrochrome bushing 3 from the magnetic field around the current leadand to assist cooling.

According to Fig. 2, the conductor 5 of Fig. 1 is replaced bya coppercylinder 8 the upper end of which has secured to it a head 9 on whichthe active portion of an electrode can be arranged. To the said tube 8is secureda copper ring 10 and to the latter a ferrochrome bushing 3. Asecond copper tube 11 of smaller diameter is arranged within the tube 8.The lower end of the tube 8 and the glass tube wall 1- are surrounded byan iron sheath 15 which is .provided with a waste tube 14 and which issecured by rubber bushings 16 and 17 to the glass tube wall 1 and thecopper tube 8 finally it is thrown through apertures 12 of the tube 8against the seal 2, so that the latter is -cooled, whereupon the liquidis carried oif via the enclosures 13 and the tube 14:.

In this modification screen 6 may be omitted if desired. Furtheropenings 12 may be placed at the lower portion of the trough formed byinner tube 11 and outer cylinder 8. In addition the direction of flow ofthe cooling fluid may be the reverse of that indicated.

It is obvious that in addition to the con a structions above describedvarious other constructions may be devised which fall within the scopeof the invention.

Having now described our invention what We claim is: I

1. A lead-in structure for an electric discharge device comprising alead, a member having relatively high hysteresis losses encircling saidlead and sealed at one end to a glass wall of the discharge device, asecond member havirg relatively low hysteresis losses and ha.ing a highthermal conductivity between said first member and said lea and a screenbetween said first member.

and said lead attached to said second member.

discharge device comprising a lead, a cylindrical member of ferro-chromeencircling said lead and embedded at one of its ends in a glass wall ofthe device, an annular ring of copper between and joining said lead andsaid ring, and a screen encircling .a

portionof said lead and attached to said ring of copper.

CORNELIS BOL.

JOHANNES JACQUES NUMANS.

2. A lead-in seal structure for an electric

